BIRDS OF THE TRES MARIAS ISLANDS. 



47 



Meaaurements of lache lai07-enoei and I. latirostris. 



Platypsaris aglaiae insularis (Ridg.) Grayson's Becard. 



Hadfostomns aglaiw var. affinis Grayson, I'roc. Boston Soc. Nat. Hist., XIV, p. 279. 



1871; Lawr., Mem. Boston Soc. Nat. Hist., II, p. 289, 1874. 

 Platypsaris insularis Ridgway, Man. N. Am. Birds, p. 325, 1887. 



The rose-throated becard was not coiuiiiou and only three specimens 

 were taken, all on Maria Madre. Tbey were found in the lieavier 

 forest oil the slopes well back from the coast, and nothing unusual was 

 noted in regard to their habits. They probably occur on Maria Mag- 

 daleiui and i)erhaps on Maria Oleofa. A considerable series of speci- 

 mens from various parts of Mexico shows that a single species of rose 

 breasted becard ranges over a large part of Mexico and has developed 

 four geographical subspecies. The ranges of these four forms may be 

 defined as follows : 



Platypsaris aglaiw (Lafr.). Eastern Mexico from northern Tamau- 

 lipas south along basal slojies of the Cordillera of Vera Cruz and 

 Tabasco to arid parts of Yucatan. (Type from viciuity of Jalajja, Vera 

 Cruz.) 



Platypsaris aglaiw sumichrasti Nelson. Humid lowlands of Vera 

 Cruz, and thence southward in similar country nearly or quite to Guate- 

 mala. (Type from Otatitlan, Vera Cruz.) 



Platypsaris aglaiw albiventris (Lawr.). West coast of Mexico from 

 the Isthmus of Tehauntepec to southern Arizona, ranging along river 

 valleys into the interior of western Mexico. (Type horn Plains of 

 Colima ) 



Platypsaris aglaiw insularis (Kidg.). Tres Marias Islands. (Type 

 from Maria Madre Island.) 



Typical specimens of insularis are much darker than typical examples 

 of alhirentris. Specimens from the coast lowlands about San Bias are 

 intermediate in color. The island birds, however, may usually be dis- 

 tinguished by their smaller bills. Back from the coast of Tepic, 

 especially in the arid river canyons at Bolanos and near Guadahijara, 

 only typical specimens of albiventris viei'&iounA. On the eastern side 

 of Mexico these two forms are paralleled by the pale bird of the foot 

 hills and adjacent interior [aglaiw] aud the darker .one of the coast 

 lowlands (sumichrasti). The color of extreme specimens of albiventris 

 is very different from that of uglaiw and insularis, but among the series 

 from western ^Mexico, where alhirentris has its home, are various inter- 

 mediate stages, some specimens approaching very closely to both the 



